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Database Provider

Author

Khan Academy

Grades

9th, 10th, 11th, 12th, AP® / College

Subjects

Science, Biology, Physics

Resource Type

  • Videos, 7 minutes, 12 seconds, CC, Subtitles

Regional Focus

Global

Impact of Changes to Trophic Pyramids

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Synopsis
  • This video describes the transfer of energy through an ecosystem, using a trophic pyramid as a model to illustrate how changes at one level can affect the other levels.
  • The video includes an excellent explanation of how energy is lost at every level of the pyramid and how environmental changes can have cascading effects on other organisms.
Teaching Tips

Positives

  • A diagram in the video provides an excellent visual model to understand the relationship between energy and biomass in different trophic levels of an ecosystem.
  • This video is an excellent resource to utilize when discussing ecology and the rippling effects of changes in an interconnected ecosystem.

Additional Prerequisites

  • Students should be somewhat familiar with food chains and the laws of thermodynamics.

Differentiation

  • It may be helpful to have students draw their own examples of trophic pyramids and practice the math problems using different quantities and environments to see how areas of high biodiversity are different from other areas.
  • To increase understanding, have students work in pairs to come up with different scenarios that would change the biomass at different levels of the pyramid. For example, how would overfishing top predators be different from a chemical leak that killed off the phytoplankton in an ocean ecosystem?
  • Trophic pyramids are an illustrative example of the laws of thermodynamics, thereby providing the opportunity for connections between physics and biology.
  • Other losses of energy and biomass due to incomplete digestion are also mentioned, which can be expanded on in lessons about decomposition, soils, microbes, fungi, and insects.
  • Related resources to consider as extensions include Cougars and Trees in a Trophic Cascade and this video on ecosystem ecology.
Scientist Notes
A trophic pyramid is another name for the food chain, with primary producers (like plants) on the bottom, and apex consumers (like humans) on the top. The transference of energy from one trophic layer to the other is really inefficient and this video explains why. This resource is recommended for teaching.
Standards
  • Science
    • LS2: Interactions, Energy, and Dynamics Within Ecosystems
      • HS-LS2-1. Use mathematical and computational representations to support explanations of factors that affect carrying capacity of ecosystems at different scales.
      • HS-LS2-2. Use mathematical representations to support and revise explanations based on evidence about factors affecting biodiversity and populations in ecosystems of different scales.
      • HS-LS2-4. Use mathematical representations to support claims for the cycling of matter and flow of energy among organisms in an ecosystem.
    • PS3: Energy
      • HS-PS3-1. Create a computational model to calculate the change in the energy of one component in a system when the change in energy of the other component(s) and energy flows in and out of the system are known.
  • English Language Arts
    • Speaking & Listening (K-12)
      • SL.9-10.2 Analyze and synthesize multiple sources of information presented in diverse media or formats to determine credibility and accuracy of each source.
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